In order to recover natural resources from subterranean formations it is often necessary to perform tasks related to exploration, monitoring, maintenance and construction in remote locations that are either difficult or impractical for personnel to reach directly. For example, boreholes may be drilled tens of thousands of meters into the earth, and in the case of offshore drilling, the borehole may be thousands of meters under water. One of the technical challenges to performing tasks in such remote locations is providing power to equipment. It is known to power downhole and undersea equipment via either stored energy or wireline connection to the surface. However, both of these techniques have disadvantages. For example, a wireline connection to the surface limits that distance at which the equipment can operate relative to the energy source, and may require a relatively significant portion of the limited volume of a borehole. Using stored energy avoids some of the disadvantages of a wireline connection to the surface, but relatively little energy can be stored in comparison to requirements because of size limitations. For example, the available volume in a borehole environment is small. Further, both wireline connection to the surface and stored energy techniques require the presence of operators, e.g., a surface vessel to either provide the wireline energy or recharge the energy storage means. Various techniques associated with energy production are described below.
U.S. Pat. No. 6,504,258, VIBRATION BASED DOWNHOLE POWER GENERATOR, describes a downhole power generator including a member that is vibrated in response to fluid flow through a housing. Vibration of the member causes a power generating assembly to generate electrical power.
U.S. Pat. No. 6,768,214, VIBRATION BASED POWER GENERATOR, describes using fluid flow through a fluid conduit to cause a member to displace or vibrate. The displacement of the member is utilized to induce strain in a piezoelectric material, thereby causing the piezoelectric material to produce electricity. Various means may be used to create turbulence in the fluid flow, thereby increasing displacement of the member, resulting in increased power output from the generator.
U.S. Pat. No. 5,839,508, DOWNHOLE APPARATUS FOR GENERATING ELECTRICAL POWER IN A WELL, describes electrical generating apparatus which connects to production tubing. In a preferred embodiment, this apparatus includes a housing having a primary flow passageway in communication with the production tubing. The housing also includes a laterally displaced side passageway communicating with the primary flow passageway such that production fluid passes upwardly towards the surface through the primary and side passageways. A flow diverter may be positioned in the housing to divert a variable amount of production fluid from the production tubing and into the side passageway.
U.S. Pat. No. 3,371,234, PIEZOELECTRIC VIBRATORS AND SYSTEMS EMBODYING THE SAME FOR CONVERTING THE MECHANICAL VIBRATION THEREOF INTO ELECTRIC ENERGY, describes use of mechanical vibrators of the piezoelectric-quartz-crystal type for converting mechanical vibrations into electric energy. The mechanical vibrators be used, for example, to detect the mechanical vibration or acceleration of a structure.
U.S. Pat. No. 4,387,318, PIEZO-ELECTRIC FLUID ELECTRIC GENERATOR, describes a device with a bending element that generates electrical power when deformed by fluid flow. The bending element is fixed to mounting means at one end and to a fin-like driving means at the other end.
U.S. Pat. No. 5,494,468, FLIPPER ENERGY SOURCE, describes a swim fin for generating electricity. The swim fin has a body which is placed under stress and deformed by water during the act of swimming. Piezoelectric devices are integrated into the swim fin body so that the deformation of the fin body generates electricity.
U.S. Pat. No. 6,011,346, APPARATUS AND METHOD FOR GENERATING ELECTRICITY FROM ENERGY IN A FLOWING STREAM OF FLUID, describes a conduit with a divider to which piezoelectric members are attached. The divider separates fluid flow into two paths, and a restrictor controls distribution of flow between the two paths. Differential pressure between the paths causes deformation of individual piezoelectric members, thereby generating electricity.
U.S. Pat. No. 6,424,079, ENERGY HARVESTING EEL, describes a power generator using an elongated, eel-like piezoelectric body that is moved by flowing water. The piezoelectric body is mounted to a spring mechanism, and moves in response to traveling vortices in the water, in a manner similar to a flag in the wind.
U.S. Pat. No. 6,433,465 B1, ENERGY-HARVESTING DEVICE USING ELECTROSTRICTIVE POLYMERS, describes a polymer material incorporated into the soles of footwear to produce energy. The resulting energy is either full-or partial-wave rectified and then, if desired, converted to a direct current (DC) voltage level for suitable battery charging.
U.S. Pat. No. 6,532,740 B1, GENERATOR EMPLOYING THE CORIOLIS EFFECT, describes a system for employing the Coriolis effect for the generation and storage of energy. The system includes a vortex chamber for rotational acceleration of superheated, supersaturated water vapor and heated air. A water intake assembly is adapted to deliver a directed flow of superheated water vapor to a lower portion of the vortex chamber while the air intake assembly is adapted to deliver a flow of heated air to the lower portion of the vortex chamber. The air intake assembly includes an electrical generator operable by airflow drawn from the air intake assembly.
U.S. Pat. No. 6,768,214, VIBRATION BASED POWER GENERATOR, describes a device with a member that is displaced in response to fluid flow in a vibratory manner. The displacement of the member is used to induce strain on a piezoelectric material, and thereby generate electricity.
U.S. Pat. No. 6,856,036 B2, INSTALLATION FOR HARVESTING KINETIC ENERGY OF OCEAN CURRENTS IN DEEPWATER, describes utilization of a semi-submersible platform and multiple, vertically oriented Darrieus-type hydraulic turbines with funnels. The turbines are located below sea level at a depth sufficient to isolate them from wave action. Electric power generators are located on a structure above water, and operate to provide electric power which is transmitted to the shore. One of the embodiments is designed to harvest energy from tidal currents in deepwater.
US 20060022555 A1, ENERGY HARVESTING SYSTEM, APPARATUS AND METHOD, describes a device that transforms acoustic energy into electrical energy for use by a sensor. The device utilizes a piezoelectric component which may be encased within an acoustic chamber. The acoustic chamber concentrates the acoustic energy.
US 20060063522 A, SELF-POWERING AUTOMATED BUILDING CONTROL COMPONENTS, describes a network of wireless radios for controlling operation of equipment, and locating assets and personnel. The wireless radios may be powered by energy generators that scavenge energy from the building, building equipment, or building environment. For example, the energy generators may utilize micro-electro-mechanical components or piezoelectric materials driven by vibrations. The energy generators may alternatively generate electrical energy from light, thermal, kinetic, radio frequency, movement or other forms of energy.
US 20050134149 A, PIEZOELECTRIC VIBRATION ENERGY HARVESTING DEVICE, describes a device having first and second masses, and first and second springs coupled to the first and second masses, respectively. A piezoelectric element is bonded between the first mass and the second spring, so that a stress applied to the second spring is applied to the piezoelectric element.
GB1116451 A, METHOD OF AND APPARATUS FOR TRANSMITTING ENERGY BY PRESSURE OSCILLATIONS IN A FLUID, describes a fluid-pressure apparatus with a branch duct of a gas or liquid-filled duct through which oscillations are transmitted by a mechanical oscillator to a receiver which is connected to a cylinder having an adjustable piston.